Thank you Purist for another extensive reply.
I've had a look again at the Esses of Watkins Glen and there is one tunnel more than I first realized there was.
If you look at this aerial view
http://www.aboveallohio.com/images/s...erial_view.jpg on the right, there are the Esses. There are tunnels going through under the track both before and after Turn 4. Both would have to be lengthened so runoff for Turns 2, 3 and 4 could be built on top of them.
When talking about access roads blocking the introduction of new safety features, the problem of Watkins Glen is relatively minor when compared to other seasoned tracks.
For example, the traditional Donnybrooke perimeter circuit of Brainerd International Speedway in Brainerd, Minnessota, where USAC ran one of its first road races back in the 60s has got only one entrance for spectators enabling them to enter the infield and to see the far end of the track from inside. That road leads over a bridge across the track, and that bridge stands in the place where a fast corner's runoff should be these days.
Instead of changing the access road, Brainerd chose to abandon this portion of the track completely, and built a somewhat slower speed shortcut that includes even a new pitlane, as the old pitlane area on the former front straight is now used as a drag strip. That must have been quite an investment.
If Brainerd International can do it, then why not Watkins Glen, as the Glen's problem would even be easier to fix?